[RASMB] sapphire windows

[Tom Laue]

Hi all-
Both marks are aligned with an optical axis. The synthetic fused silica 
windows used for UV work is grown as boules along the Z-axis. While 
mis-alignment of the axis has little effect on the absorbance 
characteristics, it is a good idea to use the mark for reproducible 
alignment.
If you mis-align the sapphire windows, you may observe vertical streaks 
through the fringes that shift in position and intensity with rotor 
speed. So do align the mark on the sapphire windows with the key way.
The fused silica windows are too "soft" for interference work and 
deformation-induced inhomogeneities in the refractive index lead to the 
fringes being washed out.
The new sapphire windows are nearly as clear in the far UV (at least to 
230 nm) and do not break. It is cost-effective to consider using 
sapphire windows for all work.
Best wishes,
Tom

Leech, AP wrote:
> Hello all,
>
> I did not realise the ticks on the sapphire windows are aligned with
> optical axes of the material - I assumed they were just handy marks
> for reproducibility of alignment. Does this make any noticeable
> difference to the fringe patterns?
>
> The quartz windows also have tick marks - do these have any special
> significance?
>
> Andrew
>
>
> Walter Stafford wrote:
>> These windows should be cut with the z-axis perpendicular to the 
>> window face. And the x-axis should be marked usually with a short 
>> metalized line.
>>
>> Ian Taylor wrote:
>>> Dear Rasmbers
>>> Does anybody know whether sapphire windows for the XLi interference 
>>> optics are required be cut with the C axis of the crystal parallel 
>>> to the window face, elimination of birefringence effects?
>>>
>>> ian
>>>
>>> Dr I A Taylor
>>>
>>> Division of Molecular Structure
>>>
>>> National Institute of Medical Research
>>>
>>> The Ridgeway
>>>
>>> Mill Hill
>>>
>>> NW7 1AA
>>>
>>> tel 0208 816 2552
>>>
>>> fax 0208 816 2580
>>>
>>> email itaylor at nimr.mrc.ac.uk <mailto:itaylor at nimr.mrc.ac.uk>
>>>
>>>
>>>
>>> ------------------------------------------------------------------------ 
>>>
>>>
>>> _______________________________________________
>>> RASMB mailing list
>>> RASMB at rasmb.bbri.org
>>> http://rasmb.bbri.org/mailman/listinfo/rasmb
>>>   
>>
>

-- 
Department of Biochemistry and Molecular Biology
University of New Hampshire
Durham, NH 03824-3544
Phone: 603-862-2459
FAX:   603-862-0031
E-mail: Tom.Laue at unh.edu
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